Shielded cask for radioactive material



D c- 9, 1959 K. ANTONSEN ETAL 3,483,380

SHIELDED CASK FOR RADIOACTIVE MATERIAL Filed April 9, 1965 10Sheets-Sheet l Dec. 9, 1969 K. ANTONSEN ETAL 3,483,380

SHIELDED CASK FOR RADIOACTIVE MATERIAL l0 Sheets-Sheet 2 Filed April 9,1965 9, 1969 K. ANTONSEN ETAL 3,483,380

SHIELDED CASK FOR RADIOACTIVE MATERIAL 1969 K. ANTONSEN ETAL 3,483,380

SHIELDED CASK FOR RADIOACTIVE MATERIAL l0 Sheets-Sheet 4 Filed April 9,1965 f1: vszzzar's A A/Z/D A VTOA/SEA/ F/CA APD FUSE/V5696 HADZEYK 444/79 M Mml-mjmflw K. ANTONSEN ETAL SHIELDED CASK FOR RADIOACTIVEMATERIAL l0 Sheets-Sheet 5 Dec. 9, 1969 Filed April 9, 1965 270a #401044w/nep Zfi D 1969 K. ANTONSEN ETAL 3,483,330

SHIELDED CASK FOR RADIOACTIVE MATERIAL Filed April 9, 1965 10Sheets-Sheet 6 Lfld AR I D 9, 1969 K. ANTONSEN ETAL 3,483,380

SHIELDED CASK FOR RADIOACTIVE MATERIAL 10 Sheets-Sheet Filed April 9,1965 ffl Lim lm, 6w

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1969 K. ANTONSEN ETAL 3,483,380

SHIELDED CASK FOR RADIOACTIVE MATERIAL l0 Sheets-Sheet 8 Filed April 9,1965 m 5 2 /Z 2 5% m [Key M A 1969 K. ANTONEEN ETAL. 3,483,380

SHIELDED CASK FOR RADIOACTIVE MATERIAL 1O Sheets-Sheet 10 Filed April 9,1965 United States Patent O 3,483,380 SHIELDED CASK FOR RADIOACTIVEMATERIAL Knud Antonsen and Richard Rosenberg, San Diego, and Hadley K.Wiard, La Mesa, Calif., assignors, by mesne assignments, to Gulf GeneralAtomic Incorporated, San

Diego, Calif, a corporation of California Filed Apr. 9, 1965, Ser. No.447,003 Int. Cl. G21f 7/00 U.S. Cl. 250-108 21 Claims ABSTRACT OF THEDISCLOSURE A shielded cask particularly adapted to receive radioactiveelements, such as nuclear fuel cells, including a housing having anaccess passageway at one end, a rack rotatably mounted in the housingand defining a plurality of compartments each adapted to receive anelement. In certain specific embodiments, means are provided for varyingthe position of the acces passageway relative to the housing, tomaintain the elements in compartments, and to shift the rack within thehousing to enable it to be supported by an interior wall of the housingfor shipment.

The present invention relates to a shielded cask for receiving, storing,transporting and delivering radioactive elements of a nuclear reactor.

It is a necessary incident to the operation of a nuclear reactor systemto periodically remove radioactive elements, such as spent fuelelements, from the nuclear reactor and to transport such radioactiveelements to vari ous places in the nuclear plant or other installations.It also may be necessary to transport and replace in the reactorradioactive elements such as fresh fuel elements. It is also necessarythat radioactive reactor elements be shipped to and from the plant.During the handling of such elements, it is very important thatpersonnel are adequately shielded from the radioactive elementsthemselves and from equipment which may be exposed to, and therebycontaminated by, the elements. Other primary considerations are the timerequired for the operation, and the cost of the equipment and/or plantstructure required.

'In presently known systems, handling and transportation of reactiveelements, such as nuclear fuel elements, by a movable shielded cask witha high element capacity frequently requires an overhead bridge ortrolley system and submergence in water unless very large isolationvalves are employed. Such plant construction and/or equipment is costly.In dry reactor systems, such as gascooled reactor systems, installationof such reactive elements in a high load capacity movable cask, whichdoes not include a movable rack arrangement such as is incorporated inthe cask of the invention, would require either a seal-tight canning ofeach of the elements and subsequent wet installation in the cask in aseparate water-filled facility, or some type of very large isolationvalve or other heavy equipment for dry installation. Again large costsare involved.

The present invention has the advantage that it provides a highcapacity, shielded cask from which elements may be rapidly loaded orunloaded through an isolation valve which is small relative to the crosssectional area of the cask while personnel and other equipment are ade-It is another object of the present invention to provide a novel andimproved shielded cask for handling a plurality of radioactive elements.

It is a more specific object of the invention to provide such a cask forreceiving, storing, transporting, and/or delivering radioactive elementsof a nuclear ireactor.

It is another object of the present invention to provide such a caskwherein radioactive elements may be loaded and unloaded through arelatively small passageway and through relatively small and less costlyisolation valve equipment while personnel and other equipment areadequately protected from radiation from the elements.

Another object is to provide such a cask into which a plurality ofradioactive elements may be loaded, or from which a plurality ofelements may be unloaded, in a minimum of time.

A more specific object of the present invention is to provide such acask which is operable to selectively position at least one compartmentof a rnulti-compartment element-receiving rack within the cask inalignment with an access passageway of the cask.

It is another more specific object of the present invention to providesuch a multi-compartrnent cask in an alternative form where compoundmovement is utilized to afford access to a large number of compartments.

It is another object of the invention to provide such a cask capable ofreceiving and delivering elements from different spaced locations whilethe cask itself is in a fixed position.

It is another object of the invention to provide such a cask thatincorporates particularly suitable handling means for positioning theelements relative to the cask.

It is another object of the invention to provide such a cask thatincludes particularly suitable means for supporting the elements in thecask.

It is also an object of the present invention to provide a novel andimproved cask in a form particularly adapted for shipment of a pluralityof elements.

It is a more specific object to provide such a shipping cask whichincorporates means for readily radially repositioning acenteredrotatable element-holding arrangement to an eccentric, non-rotatable,supported position for shipment of the elements.

It is also an object of the present invention to provide such a shieldedcask which is simple, durable, and relatively economical to produce andmaintain.

Other objects and advantages of the present invention will become moreapparent from the following description and the accompanying drawings,wherein:

FIGURE 1 is a partially broken away, fragmentary elevational view,partially in section, of a nuclear power plant illustrating inparticular the reactor of the plant, a fuel transfer cask, and a fuelshipping cask, embodying various features of the present invention;

FIGURE 2 is an enlarged side view of the fuel shipping cask shown inFIGURE 1;

FIGURE 3 is an enlarged plan view of the fuel shipping cask of FIGURE 2;

FIGURE 4 is an enlarged sectional plan view taken generally along line44 of FIGURE 2;

FIGURE 5 is an enlarged partially broken-away sectional plan view takenalong line 5-5 of FIGURE 2;

FIGURE 6 is an enlarged fragmentary sectional elevational elevationalView taken along line 6-6 of FIG- URE 3;

FIGURE 7 is an enlarged fragmentary sectional plan view taken generallyalong line 77 of FIGURE 6;

FIGURE 8 is an enlarged side sectional view of the fuel transfer caskshown in FIGURE 1, said cask having a rotary support rack arrangementand presenting a preferred form of transfer cask which embodies variousfeatures of the invention;

FIGURE 9 is a fragmentary sectional plan view on a reduced scale takengenerally along line 9-9 of FIG- URE 8;

FIGURES 10 and 11 are enlarged plan sectional views taken generallyalong lines 10-10 and 11-11, respectively, of FIGURE 8;

FIGURE 12 is an enlarged fragmentary partially broken away sidesectional view of portions of the cask shown in FIGURES 8 through 11,showing in particular the supporting and retaining structure of thecask;

FIGURES 13 and 14 are enlarged side sectional views of portions of thestructure shown in FIGURE 12;

FIGURE 15 is an enlarged side sectional view of the' grappler of thecask shown in FIGURES 8 through 14;

FIGURES 16 through 18 are sectional plan views taken generally alonglines 16-16, 17-17, and 18-18, respectively, of FIGURE 15;

FIGURE 19 is a fragmentary side sectional view of a modified form offuel transfer cask having a compoundmovement rack arrangement;

FIGURES 20 and 21 are enlarged plan sectional views taken generallyalong lines 20-20 and 21-21, respectively, of FIGURE 19; and

FIGURE 22 is an enlarged side view of a portion of the positionablegrappler carrier for the cask shown in FIGURES 19 through 21.

Briefly, a shielded cask, in accordance with the invention, forreceiving, storing, transporting, or delivering a plurality of elongatedradioactive elements of a nuclear reactor includes a closed, shieldedhousing having at least one openable access opening or passageway.Within the housing a support rack arrangement is mounted for movementrelative to the access passageway. The rack arrangement defines at leasttwo elongated compartments or channels each adapted to receive andsupport one of the elements. The rack arrangement is movable to alignany selected one of the compartments with an access passageway so thatan element can be moved through the passageway into or out of thatcompartment.

The cask can be operated remotely and the access opening may be small insize compared with the size of the storage area of the cask. Such a caskaffords positive positioning of elements in the cask, requires a minimumof shielding material and a minimum of additional equipment, and servesto minimize radiation exposure to personnel and equipment. Further, theuse of such a cask for refueling -a nuclear reactor substantiallyreduces refueling time.

NUCLEAR POWER PLANT As shown in FIGURE 1, which discloses a portion of anuclear power plant, a gas-cooled nuclear reactor which includes aprimary containment vessel 32 and a secondary containment vessel 34 ishoused within the lower level of a reactor building 36. The reactorbuilding 36 includes an intermediate wall 38 which overlies the reactor30 and is provided with an access opening 40 above the reactor vessels.A bridge 42 is movably supported over the opening 40 generally levelwith the wall 38. The bridge 42 includes tracks 44 which extendtransversely to the direction of movement of the bridge and which may bealigned with other tracks (not shown) of a track or rail system whichextends to other portions of the reactor building 36 and to otherportions of the power plant. In particular, the rail or track systemleads to a fuel storage vault (not shown) and a shipping cask loadingarea or installation 48, both of which are positioned like the reactor,below the level of the tracks. The shipping cask loading area 48 has anaccess opening 49 above it extending through the intermediate wall 38.

The track system has a centrally open construction to afford extensionof equipment and passage of material or elements through the tracks andopenings 40 4 and 45 in the wall 38. A self-propelled wheeled fueltransfer cask 50, hereinafter described in detail, is movable along thetracks 44 from the reactor 30 to the fuelstorage vault (not shown) andto the shipping cask loading area 48. The lower portion of the cask 50extends, as shown in FIGURE 1, through the open track construction tocommunicate with the reactor and other equipment in the lower level.

The combined movement of the bridge 42 relative to the opening 40, andthe fuel transfer cask 50 relative to the bridge, serve to position thecask over a preselected one of a plurality of control rod nozzles orspecial refueling nozzles 51 of the reactor. The nozzles 51 extendupwardly from the primary containment vessel 32 and are in communicationwith the reactor core 52 which is housed within the vessel 32. The core52 is a generally cylindrical package or bundle of elongated uprightcore elements which include control rod guide tube elements 53, controlrod elements, and fuel rod elements 54. The core may also be surroundedby suitable reflector elements (not shown). Preparatory to refueling,either the control rod drive mechanism with its two associated controlrod elements, or, in the case of a special refueling nozzle, theshielding plug, in the pre-selected nozzle is removed from the reactor.In brief, the fuel transfer cask 50 is then positioned over andconnected to the selected nozzle 51. Spent elements are transferred fromthe reactor through the nozzle and into the transfer cask. The cask isalso used to transfer fresh elements into the reactor.

The cask 50 transports spent radioactive elements to a fuel storagevault (not shown) in which they are stored for a cooling period. Thecooled elements are subsequently taken by the fuel transfer cask 50 anddelivered to a fuel shipping cask 60 (FIGURES 1 to 7), disposed in thelower level loading area 48, as shown in FIG- URE 1. More specifically,the fuel transfer cask 50 is moved along the tracks 44 to a positionover the opening 49 leading to the area 48 from which position the cask50 delivers the spent elements to the fuel shipping cask 60. The fueltransfer cask 50 is also used to transfer fresh elements from theshipping cask 60 to the reactor.

FUEL SHIPPING CASK The fuel shipping cask 60- is shown in FIGURES 2through 7. In general, the illustrated cask 60 includes an elongatedgenerally cylindrical closed shielded housing or casing 62 positionablefor loading and unloading with its longitudinal axis vertical. Forconvenience, the cask and its components will be described in terms ofits vertically extending operational position. The casing 62defines aclosed cavity 65 within which a rack or support arrangement 66 (FIGS. 6and 7) is supported for rotation about the vertical central axis of thecasing.

The rack arrangement 66 defines a plurality of elongated verticallyextending channels or compartments 68 which are each adapted to receiveone of the reactor elements. As shown particularly in FIGURE 7, theillustrated rack arrangement 66 provides four concentric rings or loopsof compartments 68, and there are four relatively small openable accessopenings or passageways 70 in the upper end of the casing 62 (FIG. 3)which are each radially aligned with one of the rings of compartments.The cask 60 further includes driving means 72 (FIG. 6) which is operableto rotate the rack arrangement 66 to align a pre-selected compartment 68with an access opening 70.

Now referring more specifically to the fuel shipping cask 60 illustratedin FIGURES 2 through 7, the generally cylindrical shielded housing orcasing 62 for the cask is positioned in vertically extending position,as shown in FIGURES 2 and 6', for loading and unloading, and, in thisregard, is provided with a pair of opposed trunnions 73 and a secondpair of. trunnions 73!), the latter of which provide suitableattachments for raising and lowering apparatus, such as a pair ofhydraulically operated cylinders (not shown). For shipment, the cask ismounted on its side in horizontally extending position (not shown) on aheavy duty railroad fiatcar 74 with the trunnions 73 received insuitable mating supports 73a on the railroad car. Other externalequipment (not shown) is used to complete the supporting and securing ofthe cask for shipment. Referring to FIGURE 1, the railroad car 74 ismoved along suitable tracks 75 into the loading area 48 and the cask ispivoted about the pair of trunnions 73 at its lower end to the uprightposition where the access passageways 70 are uppermost. The railroad caris positioned so that the access passageways 70 are aligned below theopening 49 above the loading area. The casing 62 includes generally areceptacle or base section 76 and a cover or lid section 78.

The illustrated base section 76 includes an exterior shell 76a and aninterior shell 7617 (FIG. 6). The shells 76a and 76b are generallycylindrical vertically-extending containers open at their upper ends andclosed at their lower ends. The interior shell 76b is somewhat smallerthan the exterior shell 76a being located centrally of and spaced fromthe cylindrical wall of the exterior shell by three elongated,vertically extending, semicircular pipe sections 79 (FIG. 4) equallyspaced circumferentially around the interior shell. The lower walls ofthe shells are also spaced from each other, and the space between theshells as well as the cavities of the three semicircular pipes 79, anfilled with lead FIGS. 5 and 7). The upper edges of the shell aregenerally level and connected together by a generally horizontal,annular, interconnecting ring structure 82 (FIG. 6) which defines aninternal annular recess 84 extending around the inside of the upper edgeof the base section 76.

The illustrated cover or lid section 78 (FIGS. 2, 3 and 6) is in theform of a generally fiat circular disk or plate that is secured over theopen upper end of the base section 76 to complete the shielded casing62. The underside of the cover section 78 is formed with a downwardlyextending centrally located cylindrical portion 86 which is adapted tomate with. the annular recess 84 at the upper edge of the base section76 when the cover section 78 is positioned on the base section asillustrated in FIGURE 6. The cover section 78 is secured in place by aplurality of screws 88 disposed circumferentially adjacent the edge ofthe cover section (FIGS. 2 and 3).

When the cover section 78 is secured on the base section 76 to providethe shielded casing 62, the two sections define internally thereof thegenerally cylindrical upright cavity 64. The rack or support arrangement66 is rotatably supported within the cavity 64, as hereinafterdescribed.

As best shown in FIGURES 6 and 7, the illustrated rack arrangement 66includes a generally circular horizontal lower support plate 102 havinga somewhat smaller diameter than the Casing interior. The support plate102 is supported generally coaxially within the casing and spaced ashort distance above the lower end wall of the casing. Secured upon andsupported by the support plate 102 are five generally cylindrical tubesor barrels 104 which are secured with their axes generally vertical andconcentric with the vertical axis of the casing. The cylindrical barrels104 are generally of equal height with their upper edges spaced a shortdistance below the cover section 78, but vary in diameter from thelargest outermost barrel 104a, which is approximately the diameter ofthe plate 102, through intermediate barrels 104b, 1040 and 104d, to thesmaller and innermost barrel 1046. Thus, the barrels 104 are ingenerally concentric telescoped relation, secured at their lower edgesto the horizontal plate 102, and define four generally cylindrically orannular spaces between adjacent barrels. The annular spaces aredesignated a, b, c and d, with largest annular space a being definedinwardly of barrel 104a and outwardly of barrel 104b, with space 11defined inwardly of barrel 6 104b, with space 0 defined inwardly ofbarrel 104s, and with space 0! defined inwardly of barrel 104d. It mayalso be noted that the spacing between the adjacent barrels 104- isapproximately equal so that the radial widths of the various annular orring-like spaces are approximately equal to one another.

Each of the annular spaces is subdivided into the individualelement-containing channels or compartments 68 of the rack arrangement.More particularly, each of the annular spaces is provided with aplurality of generally vertical radially extending dividers 106 whichare secured in position between adjacent barrels 104. The dividers 106in adjacent annular spaces are generally offset or staggered to providestability to the rack arrangement. As shown in FIGURE 7, the rackarrangement 66 of the illustrated cask 60 provides six elongatedvertical channels or compartments 68 around the innermost space a,twelve such compartments around the next intermediate annular space a,eighteen such compartments around the next intermediate annular space b,and twenty-four such compartments around the outermost annular space afor a total of sixty compartments.

As shown in FIGURE 7, there is secured in a corner of each compartment68 of the intermediate annular space 0 an elongated vertically disposedabsorber rod 110 which serves, in case of an emergency as where the caskbecomes flooded by a moderating .material such as water, to absorbneutrons and thereby ensure that the fuel in the cask 60 does not becomecritical. Each of the illustrated rods 110 is in the form of a hollowtube capped with steel end plugs and filled with a suitable neutronabsorbing material such as boron carbide granules.

As shown in FIGURE 6, a generally circular upper bearing race or ring112 is secured to the underside of the horizontal support plate 102 ininwardly spaced relation to the edge of the plate approximately half thedistance to the center thereof. Secured directly beneath the bearingrace 112 is a generally circular bearing cage or ring 114. The race 112and the cage 114 are secured to the plate 102 as by means of screws 116.The illustrated bearing cage 114 is provided with a plurality ofcircumferentially spaced-apart recesses in each of which is partiallyreceived a bearing-ball 118. Disposed immediately below the cage or ring114 is a generally circular lower bearing race or ring which is securedto the horizontal lower end wall of the interior shell 76b as by meansof screws 121. The bearing-balls 118 abut the lower race 120 tovertically support the rack arrangement 66 while permitting it to rotatewith a minimum of friction between thr rack arrangement and thesupporting parts.

The illustrated rack arrangement includes a generally tubular uppercollar or bushing 122 which is mechanically secured in the upper end ofthe innermost and smallest barrel 104a. A generally tubular lower collaror bushing 124 is secured in the lower end of the barrel 104e. Thehorizontal support plate 102 is provided with a central opening oraperture through which the lower end of the bushing 124 extendsdownwardly. The lower end of the bushing 124 is provided with anoutwardly extending flange which is secured to the underside of theplate 102 as by means of screws 126. The illustrated bushings 122 and124 are both generally cylindrical externally to mate with therespective ends of the cylindrical barrel 104e, while the centralopening through each of them is enlarged at either end to provide anarrowed or restricted intermediate annular contact area or zone 122aand 124a, respectively, for each bushing.

Received in, and extending through, the upper bushing 122 is anelongated vertically extending upper cam 128 which includes a generallycylindrically lower portion, an irregularly shaped upper portion, and anupper extension. The upper portion of the cam 128 is cut away to form arecess on the left, as viewed in FIGURE 6, and is provided with anupwardly outwardly enlarging wedge or projection 12811 on the right. Theupper end of the cylindrical lower portion is recessed inwardly to meetthe lower inward end of the wedge 128a. When the cask is in operatingposition, the lower portion is received in the bushing 122, as shown inFIGURE 6, with that lower portion engaging the contact zone 12.211 ofthe bushing. The upper extension of the cam 128 is connected to thecasing 62 in a manner permitting vertical movement but preventingrotation of the cam. More particularly, the upper extension is receivedin a recess in the under-surface of the cover section 78. A pair of keys130 are arranged between the extension and the cover section 78 toprevent relative rotation between the cam and the casing whilepermitting vertical movement of the cam.

An elongated generally tubular vertically extending lower cam 132 isreceived by the lower bushing 134. The lower cam 132 is somewhat similarin construction to the upper cam 128, having a generally cylindricallower end portion adjacent an irregularly shaped upper portion formed toprovide a recess at the left and a wedge or projection 132a at theright. The lower cam 132 is connected through a pair of keys 134 and ahousing 135 to the base section 76 of the casing in a manner permittingvertical movement but preventing rotation of the 'lower cam.

The lower cam 132 is provided with a generally cylindricalvertically-extending threaded central aperture through which a generallycylindrical threaded lower center shaft 136 is rotatably disposed. Thelower end of the shaft 136 is rotatably mounted in the housing 135 whichis supported in the lower end wall of the base section 76. The upper endof the shaft 136 is secured to the lower end of a cylindricalvertically-extending tube or hollow rod 140. The tube 140 extendsupwardly through the center of the rack within the innermost barrel104s. The upper end of the tube 140 is secured to the lower end of agenerally cylindrical vertically extending threaded upper center shaft142. The shafts 136 and 142 and the center tube 140 thus comprise aunitary center shaft construction. The upper end of the shaft 142 isrotatably threaded into a threaded central aperture or recess 144 in thelower end of the upper cam 128.

Thus, when the cask is in its vertically extending operational positionand the parts are in the respective positions shown in FIGURE 6, therack arrangement 66 is rotatable about the central axle assembly whichcom prises the cams 128 and 132 as well as the rotatable center shaftconstruction. When the cask is in this operational centered position,the central axle assembly is rotationally fixed as will be understoodfrom the further description. The rotational engagement between the rackarrangement and the center axle assembly is between the upper and lowercontact zones 122a and 124a of the bushings and the cylindrical lowerportions of the cams 128 and 132. The rack arrangement 66, as notedabove, is supported vertically by the bearing-balls 118 for low-frictionrotational movement.

As shown in FIGURES and 6, the lower end wall of the interior shell 76bdefines a generally rectangular well or recess 146 located centrally ofthe casing. The well 146 is adapted to receive the rectangular housing135, within which the lower shaft 136 is rotatably supported, and torestrict rotational movement of the housing. The illustrated housing 135includes a generally rectangular upwardly-open body portion 135a and ahori zontal cover or lid portion 135b. The lower portion of the shaft136 extends downwardly through a suitable hearing in the cover portion135b with the lower end of the shaft rotatably supported in a suitablebearing in the lower wall of the base portion 135a. The cover portion1351) includes a generally central, upwardly-open, recessed area orcavity around the shaft 136 where the lower end of the cam 132 isreceived and is secured against rotation by the keys 134.

As shown in FIGURE 6, within the housing 135 and fixed on the lowerportion of the shaft 136, is a centering worm gear 150 which engages acentering worm 152 fixed to a horizontal shaft 154 rotationallysupported in the housing 135. The shaft 154 is adapted to operativelyconnect to suitable motor means (not shown) through a closablepassageway 156 which, as shown in FIGURE 5, extends from the recess 146to the exterior of the casing. When the cask is positioned in a suitableinstallation such as the loading area 48, the shaft 154 is operativelyconnected to motor means of the installation. When the cask is beingshipped, the passageway 156 will be sealed.

Rotation of the centering worm 152 rotates the worm gear 150 and thecenter shaft construction to move the cams 128 and 132 vertically. Morespecifically, the rotation of the threaded shafts 142 and 136, whichcomprise the center shaft construction, move the threaded cams 128 and132 either both upwardly or both downwardly due to the fact that bothare threadedly engaged with the shafts but are keyed to prevent theirrotation. The cams 128 and 132 are shown in FIGURE 6 in their elevatedor uppermost positions where the cylindrical lower portions extendthrough the contact areas 122a and 124a of the bushings to center therack arrangement 66 in its operating rotational position.

Suitable rotation of the center shaft construction moves or shifts therack arrangement laterally of its center position, as shown in FIGURE 6,to the right to an offset or eccentric position. More specifically, thecams 128 and 132 are moved downwardly by the rotation of the centershaft construction. The downward movement of the projections 128a and132a of the respective cams 128 and 132 shift or move the rackarrangement to the right and maintain it in that position. Then, whenthe entire cask is tilted or pivoted toward the right and onto its sidefor shipment, the rack arrangement will rest against and be supported bythe casing rather than being suspended on the central axle assembly.This is desirable since it provides more uniform support of the rackarrangement.

A lock screw 157 is provided in the center of the cover section 78 forabutting the upper end of the cam 128 and locking the central axleassembly and the rack arrangement against linear movement. The lockscrew 157 is operated through an aligned closable port 158 in the coversection 78.

When the cask is again pivoted to the upright position for loading orunloading, the rack arrangement is laterally shifted by rotation of thecenter shaft construction back to its centered position (FIGURE 6) topermit rotational positioning of the rack arrangement.

The rack driving means, designated generally 72, is illustrated best inFIGURE 6 within a driving means housing 160 disposed adjacent one sideof the lower end of the casing. More particularly, the housing 160 isdisposed in an upwardly open cavity or well 161 (FIGURE 5) in thehorizontal lower wall portion of the interior shell- 76b. The housing160, as viewed in plan, is generally rectangular, with one end beingsemi-circular and conforms to the shape of the well 161 which is ofsimilar configuration, the semicircular end of the housing beingdirected radially outwardly to a point immediately adjacent thecylindrical wall of the casing. Extending from the radially inward endof the well 161 to the exterior of the casing is a generally tubularclosable passageway 162. The passageway 162 extends generally parallelto the passageway 156, and its outer end is spaced relatively closely tothe outer end of the passageway 156 at one side of the cask.

The illustrated housing 160 includes an upwardly open base portion 160aand an overlying horizontal cove or lid portion 16%. A vertical shaft163 is rotatably supported in suitable bearings in the bottom wall ofthe housing base portion 160a and in the cover portion 160]). A driveworm gear 164 is fixedly secured to the shaft 163 and is meshed with adrive worm 166. The worm 166 is fixedly secured to a horizontal shaft168 rotatably supported by the housing 160. The horizontal shaft 168 isaligned with the passageway 162, through which it is operativelyconnected to motor means (not shown) of the installation, when the cask60 is supported in operative upright position in a suitable installationsuch as the loading area 48.

The upper end of the vertical shaft 163 extends outwardly of the housing160 and has fixed to it a spur gear 170. When the rack arrangement 66 isin its centered operative position, the gear 170 meshes with a generallycircular internal ring gear 172 secured as by means of screws 174 to theunderside of the horizontal plate 102 of the rotary rack arrangement atthe periphery of that plate. The selective operation of the associatedmotor means serves to rotate the rack arrangement. The matchingconfiguration of the housing 160 and its well 161 prevents rotation ofthe housing.

An access, service or emergency port 176 is provided at the lower end ofthe side wall of the casing opposite the ring gear 172 and radiallyoutwardly of the rack driving means 72 to permit manual rotation of therack arrangement. As illustrated in FIGURE 6, a shielding or sealingplug 178 is normally removably disposed in the port 176 to close theport. An outer or exterior port cover 180 is removably secured over theoutside of the port 176.

FIGURE 6 also illustrates indicating means 182 for the cask (located inthe left side of the bottom of the cask as viewed in the drawing) whichincludes a micro-switch 184 and a box receptacle 185 that is secured asby means of screws 186 in a port 188 through the horizontal bottom wallof the casing. The switch 184 is positioned to be actuated by cam 190secured to the underside of the horizontal support plate 102 of the rackarrangement 66 intermediate the outer edge of the plate and the ring ofsupporting bearing-balls 118. The rotation of the rack arangement servesto operate the switch 184 to indicate the rotational position of therack arrangement.

As noted above, the fuel rod elements 54 and control rod guide tubeelements 53 are inserted and removed from the cask 60 through the accessopenings or passageways 70 in the cover section 78 of the cask. Each ofthe illustrated access passageways 70 is generally cylindrical andvertically extending, having a larger diameter portion at its upper endto provide a support shoulder 192. As shown in FIGURES 3 and 6, theaccess passageways 70 are arranged along the centerline of the coversection 78 with one passageway radially aligned over each annular orring-like space a-d of the rack arrangement 66. Because of space andshielding requirements, two of the access passageways 70 are located onone side of the cask, while the other two passageways are on the otherside of the cask: one access passageway is over the outermost annularspace a, while the other passageway on that side of center is over thealternately inward space 0n the other side of center, one passageway isover the innermost space d, and another passageway is over the alternatespace b. As shown best in FIGURE 3, the size of each passageway is smallrelative to the storage area of the cask in plan so that the isolationvalve required for moving an element into or out of the cask is quitesmall in comparison to the cross section of storage space in the cask.

The illustrated access passageways 70 are normally closed and sealed,each receiving a generally cylindrical shielding plug or insert 194.The" lower end of each of the plugs 194 is provided with a reduceddiameter whereby each plug is supported within a passageway 70 by theannular shoulder 192 of that passageway. The uppermost end of each ofthe passageways 70 is threaded to receive a mated locking or securingnut 196 which serves to maintain the shielding plug 194 in thepassageway.

The rack arrangement 66 may be rotated by means of the gears 170 and 172to position any preselected channel or compartment 68 below the accessopening 70 asso ment 53) to be placed into or removed from thatcompartment. The rack may be repeatedly rotated to provide access tosuccessive compartments until the cask is fully or partially filled oremptied. For shipment, the rack arrangement is shifted, as noted above,so that its weight is directly supported by the casing when the cask istilted onto its side into shipping position.

The illustrated cask 60 may be handled or shipped as a shielded, sealedself-contained integral unit. The illustrated cask provides adequateshielding for personnel and handling equipment during loading,unloading, shipment and storage for indefinite periods of time.

FUEL TRANSFER CASK WITH SINGLE MOVE- MENT ROTARY RACK ARRANGEMENT Theshielded fuel transfer cask 50, which has a single motion rotary rackarrangement, is shown generally in FIGURE 1 and in further detail inFIGURES 8 through 18. The cask 50 illustrates a preferred form of fueltransfer cask and is illustrative of a reactor-element receiving,transporting, and delivering cask of the present invention.

Broadly, the operation of the fuel transfer cask 50 is to receive ordeliver-one at a timea supply of fuel rod elements 54 and/ or controlrod guide tube elements 53, and to transport a number of such elementsbetween the reactor, storage facilities, and shipping facilities.

Briefly, the illustrated fuel transfer cask 50 includes a generallycylindrical, upright, closed, shielded casing or housing 200 which ismounted on a wheeled carriage 202 (FIGURE 1) movable along the rail ortrack system 44 of the nuclear power plant. The casing 200 defines aninternal cavity 204 (FIGURE 8) within which a generally cylindrical rackarrangement 206 is supported for rotation about the vertical centralaxis of the cask. The rack arrangement 206 defines a plurality ofelongated vertically extending compartments or channels 208 (FIGURE 10),each of which is adapted to receive one of the reactor elements 53 or54. The illustrated casing 200 also includes a relatively small openableaccess passageway 210 in its lower end (FIGURE 8) with which each of thecompartments 208 of the rack arrangement is adapted to vertically alignincident to the rotation of the rack arrangement. Suitable rack drivingmeans 212 are provided on the cask for selectively rotating the rackarrangement to align determined compartments with the access passageway.A grappler 214 for releasably connecting to an element and moving itinto or out of a compartment is disposed in the upper end of the casing200 above the rotary rack arrangement.

For refueling of the reactor 30, the fuel transfer cask 50 is fixedlypositioned over the reactor 30, as shown in FIG- URE 1, and inconjunction with the operation of an isolation valve (not shown), theaccess passageway 210 of the cask is put into communication with theinterior of the reactor through a selected empty control rod orrefueling nozzle 51 which serves as an access port or passageway to thereactor interior. The selected control rod or refueling nozzle 51 isprepared for this use by' the prior removal of the" control rod drivemechanism or shielding plug which the nozzle ordinarily contains. Thepositioning of the fuel transfer cask 50 over the selected nozzle isachieved by the combination movement, as described above, of the caskitself and of the bridge 42. Once the cask is connected to the reactor,the cask is in a fixed position laterally or in horizontal directions,and it is not moved until the loading or unloading of the cask iscompleted.

The unloading and loading of radioactive elements from and to theportion of the reactor core serviced by each nozzle involves twodistinct phases or steps. For unloading, first, the seven centerelements, i.e., the elements directly below the selected nozzle, arelifted from the reactor into the fuel transfer cask 50 by the directaction of the grappler 214 of the cask. Second, the cask 50 is removed,a fuel transfer machine (not shown) is inserted into the selectednozzle, and the cask 50 is replaced over the nozzle. Additional or outerelements which are laterally displaced from positions directly belowthat nozzle are individually removed from the reactor core by the fueltransfer machine. The fuel transfer machine delivers each element to thegrappler 214 of the fuel transfer cask which lifts the element into thecask. For loading, the steps or phases are reversed.

While the fuel transfer machine delivers all outer elements to thegrappler in a single delivery position, the center elements are each ina different lateral position. Inasmuch as the cask is laterally fixed inposition once it is connected to a reactor nozzle, but the centerelements are located in various positions, the access passageway 210 andthe grappler 214 of the illustrated cask arelaterally movable orpositionable so that they can be aligned with each of the centerelements. The alternative of rerepositioning of the cask 50 for eachcenter element is undesirable since it would involve appreciable time.Similarly, the provision of a large passageway with only the grapplerbeing laterally movable is undesirable as requiring at least a largerand more expensive door arrangement on the cask to deal with theincreased escape outlet for radioactivity.

After the cask 50 has been loaded with radioactive elements from thecore, the elements are transported to a storage vault into which theyare transfererd from the cask and retained for a cooling period of somemonths.

The fuel transfer cask 50 is used subsequently to take cooled elementsfrom the storage facility, transport them to a fuel shipping cask, andload them into the shipping cask for shipment to a suitable fuelreprocessing plant.

While fresh fuel elements made from new fuel may not require suchshielding as in the case of spent fuel elements, the cask 50 is used totransport fresh but radioactive fuel elements made from reprocessed fuelfrom a storage facility or directly from a shipping cask to the reactor,and to load the reactor with the elements.

When elements are being transferred between a shipping cask, such as theillustrated cask 60, and the transfer cask 50, the shipping cask 60 issupported in the lower-level loading area 48 and the transfer cask 50 ispositioned directly above it. The respective rack arrangements of thetwo casks are independently rotated to successively index or align thecompartment containing the element to be transferred with the emptycompartment of the other cask into which the element is to be loaded.This transfer operation between casks 50 and 60 is facilitated withadequate protection against radiation exposure to personnel and otherequipment by a relatively small isolation valve that affords passage ofthe elements through the passageway 49 of the shipping cask loading areaor installation 48.

Casing Now considering the fuel transfer cask 50 in further detail, asshown best in FIGURE 8, the generally cylindrical upright closedshielded casing or housing 200 defines therein the generally cylindricalinternal cavity 204. The walls of the illustrated casing or housing 200may be of a suitable shielding construction, as by including an innerand outer shell or layer of a material such as steel with anintermediate layer of a shielding material such as lead.

The illustrated cask is provided with a door arrangement 216 at itslower end operable to provide the openable and positionable accesspassageway or opening 210 of the cask. The illustrated door arrangement216 comprises two sections: a smaller inner section 216a and a largerouter section 2161). The sections 216:: and 21 6b are each provided withan aperture 210a and 210b, respectively. The apertures 210a and 210b aremoved relative to one another by the relative movement of the two doorsections 216a and 21617 to either align with one another to provide theaccess passageway 210 or to be out of alignment with one another toprovide a sealed closure to the interior of the cask.

More particularly, as shown in FIGURES 8 and 9, the short, generallycylindrical, outer door section 21611 is supported generally centrallyin the open lower end of the casing with its axis vertical. The section2161) includes the aperture 210b which extends vertically through thesection, but which is also of oval configuration in plan cross section(FIGURE 9) and is positioned with one of its ends located cenatrally ofthe section and with the remainder thereof extending radially of thesection. The hole 210a of the section 216a is of similar configurationbut is offset relative to the axis of the section with its longitudinalor principal axis lying on a non-diametrical chord of the section whenviewed in plan (FIGURE 9). A generally circular horizontal internal ringgear 220 is rotatably supported from the underside of the outer section2161). The gear 220 is generally coaxial with the outer section 21617and is rotatable about the axis of the section. The outer section 216bis provided with a generally cylindrical vertical cavity or recess inits undersurface in which the mating generally cylindrical inner section216a is received. The recess is positioned eccentrically of the outersection 21612, and while it is generally below the aperture 21% and incommunication therewith, it is positioned with its center or axis 221(FIGURE 9) angularly offset from the aperture 210k.

The inner section 216a is supported in the recess by suitable bearingsfor rotation about its own axis and includes the aperture 210a which iselongated and extends transversely across the cylindrical section 216aoffset to one side of its axis. A small external ring gear 222 issecured to the underside of the inner section 216a and engages thelarger internal ring gear 220. Rotation of the larger ring gear 220, bysuitable selectively-operable dooropening driving means 224 on thecasing (FIGURE 9), rotates the smaller ring gear 222 and the innersection 216a relative to the outer section 216b to position theapertures 210a and 21% into and out of vertical alignment.

More particularly, the apertures 210a and 21% are shown in fullalignment in FIGURES 8 and 9 to provide the fully open access passageway210. The passageway 210 is thus formed by the aperture 210a aligningwith the aperture 210b, with the upper aperture 21% defining theposition of the passageway. As shown best in FIG- URE 9, the fully openpassageway 210 extends radially outward from the center of the cask, andas will be seen, when fully open, it can afford access to a centerchannel or compartment 208 as well as to one outer compartment. When theinner section 216a is rotated about its axis, which coincides with thecenter 221 of the mating recess, the aperture 210a can be brought to theposition shown in broken line in FIGURE 9 to completely close the cask,or can be rotated to an intermediate position (not shown) where onlyportions of the apertures 210a and 21% are aligned to provide a smalleraccess passageway to either the center compartment of the cask or anouter compartment. It should be noted that even the fully openpassageway 210 is relatively small compared to the cross section of thestorage area of the cask and that the partially aligned aperturesprovide an even smaller passageway.

The outer section 216b is supported for rotation about the verticalcenter axis of the casing by an annular hearing 226 between the loweredge of the cylindrical wall of the section 216b and the casing. Theupper portion of the section 21617 has a reduced diameter to provide anannular horizontal ledge 228 on which a circular ring bevel gear 230 ismounted, The ring gear 230 is engaged by a bevel gear 232 which issecured on the end ofa horizontal shaft structure 233 that extendsoutwardly through and is rotatably supported in the adjacent casingwall. The shaft structure 233 is in driving connection with aselectively-operable door-positioning driving means 234 mounted on theoutside of the casing. Operation of this driving means 234 serves torotate both door sections as a unit to selectively position thepassageway 210 laterally of the casing to facilitate handling of thecenter elements which, as explained above, must each be handled directlyby the cask 50 in laterally different positions.

A generally cylindrical annular shield skirt 235 is disposed externallyaround the lower end of the casing 200. A generally horizontal annularflange 236 is fixed to the casing wall above the skirt 235. Thefiange236 supports a selectively operable jack mechanism including a worm gearrack 238, a flexible drive shaft 238a and a gear motor 239 (FIG. 9)which is operatively connected to the skirt 235 and which functions toraise and lower the skirt incident to connecting the cask to otherequipment such as an isolation valve for transfer of elements to or fromthe cask.

Rack arrangement The rack arrangement or means 206 for the illustratedfuel transfer cask 50 is disposed in the cavity 204 above the doorarrangement 216. The illustrated rack arrangement 206 is a generallycylindrical, vertically extending, open structure supported for rotationabout the central axis of the casing. The rack arrangement 206 includesa horizontal, generally circular, upper rack plate 240 which extendsacross the cavity 204 intermediate its height and is supported forrotation by a suitable annular bearing 242 between the outer edge of theplate 240 and the adjacent inner wall of the casing. Suspended from theplate 240 are a plurality of downwardly extending vertical support andguide rods 244. Supported at spaced intervals along the rods 244 are aplurality of horizontal, generally circular channel-defining plates 246.Suspended from the lowermost plate 246 are a plurality of spacedvertical bars 247 which support at their lower ends a generallycircular, horizontal lower rack plate 248 (FIGURE 11) that extendsacross the cavity 204 just above the door arrangement 216. An annularlower flange structure 249 between the lower rack plate 248 and theadjacent casing wall laterally positions and maintains the lower end ofthe rack arrangement, particularly incident to its rotation. A generallytubular vertical shell structure 250 is supported in the cavity 204around the rack arrangement and spaced from the casing inner wall.

The channel-forming plates 246 and the lower rack plate 248 are eachformed to provide seven generally circular apertures 251 which arevertically aligned to define the seven elongated vertical compartments,channels or racks 208 of the illustrated rack arrangement 206. As shownbest in FIGURE 10, the vertical rods 244 are disposed around theperiphery of the channel-forming apertures 251 to partially define thechannels and maintain the reactor elements moving through the channelsin proper vertical alignment, The illustrated rack arrangement 206 isprovided with a center compartment and six outer compartments annularlyarranged around the center compartment. These seven compartments arerelatively disposed in positions corresponding to the positions of theseven center fuel elements in the core.

A circular ring gear 252 is secured to the upper sur face of the upperrack plate 240 and is engaged by a gear 254 secured on the end of aradially extending horizontal shaft structure 256. The shaft structure256 extends outwardly through and is rotatably supported in the casingwall and is in driving engagement with the selectively-operable rackdriving means 212 mounted on the outside of the casing. The operation ofthe rack driving means 212 serves to rotate the rack arrangement 206 toany desired position.

The illustrated fuel transfer cask 50 includes a retaining mechanism 260that is operable to selectively support and maintain reactor elementswithin channels 208 into which they have been positioned.

As shown best in FIGURES ll, 12 and 14, an elongated normallyhorizontally disposed support bar or platform 262 is provided at thelower end of each channel 208. Each bar 262 is pivotally supported atone end by the lower rack plate 248 adjacent to one of thechannelforming apertures 251 in the plate for rotation about ahorizontally disposed pin 264 (FIG. 14) so as to permit its movementbetween a vertical, raised, open position (shown in broken line) and ahorizontal, lowered, or closed, supporting position (shown in fullline). When a bar 262 is raised, it is positioned sufliciently out ofthe associated channel or compartment 208 so that it will not obstructmovement of an element or handling means through the channel. When a baris lowered, it extends horizontally transversely across the associatedchannel with its free outer end resting on a block 265 mounted on theplate 248 across the aperture 251 from where the bar 262 is supported,to thereby support the element 54 in the channel (FIG. 12).. The pivotedend of each bar 262 is formed with teeth and engages a toothed block 266that is secured to the lower end of a vertically extending rod 268. Eachrod 268 is supported by the plates 246 for vertical movement and isconnected at its upper end, through a compression spring 270, to anactuator pin 272 that is supported by the upper rack plate 240 forvertical movement.

More particularly, each actuator pin 272 is supported in a generallytubular, vertical, pin housing 275 for vertical movement. The housings275 are supported by and extend downwardly from the upper rack plate240. A biasing spring 276 in each housing 275 urges the associated pin272 upwardly to a raised position where its upper end extends above theplate 240 as shown in FIG- URE 14. Suspended from the lower end of eachpin 272 is a generally tubular vertical, connector housing 278. Eachhousing 278 is open at its lower end to receive the spring 270 and aguide member 279 that is secured to the upper end of the associatedvertical rod 268. When a pin 272 and its rod 268 are so raised, theassociated support bar 262 is in its horizontal closed position as shownin FIGURE 14.

The pins 272 are actuated to open the channels by a horizontal actuatingplate 280 supported across the cavity 204 above the rack arrangement forvertical movement. More specifically a plurality of spaced studs 281that are secured to the actuating plate 280 each extend downwardlythrough a suitable aperture in the upper rack plate 240 into a tubular,vertical, cushion housing 282 secured to the plate 240 and extendingdownwardly therefrom. The lower end of each housing 282 is closed and acompression spring 283 is disposed in each housing to resilientlysupport the actuating plate 280 and permit its downward movement.

Driving means 283 and jack mechanisms 285 are supported by suitablebrackets on the casing inner wall above the actuator plate 280. Thedriving means 284 operates the jack mechanisms 285 to lower the plate280 against the springs 283. In particular, the lower ends of verticallymovable shafts or pins 286 of the jack mechanisms 285 are received in anupwardly open annular slot or trough 287 formed in the upper surface ofthe plate 280. This construction permits the plate 280 which is mountedon the rack arrangement to rotate with the latter while a drivingengagement is maintained between the plate 280 and the fixed jackmechanisms 285.

When the actuating plate 280 is lowered to depress the pins 272, thesupport bars 262 are pivoted upwardly to their vertical open positions.With regard to a compartment already containing an element, theassocated bar 262 is held down by the element and the associated rod 268remains stationary, the downward movement of the associated actuator pin272 being absorbed by its compression spring 270. When an element is inplace and it is desired to close the compartment, the actuating plate280 is elevated to release the pins 272 and the bar associated with thatchannel or compartment is allowed to tilt back to its lowered closedposition. Of course, the

reactor element initially is raised far enough in the compartment topermit the downward swing of the bar; then the element may be loweredonto the bar and deposited there. The bar, as noted above, will supportthe element in the compartment.

As shown best in FIGURE 8 a grappler or handling mechanism or means 290is disposed in the upper end of the cavity 204. It is thus positionedabove the rack arrangement 206 and operates in general to selectivelyposition the grappler 214 in any desired position laterally of the rackarrangement as well as to raise, lower and operate the grappler.

-A generally circular, horizontal transverse plate 291 is secured acrossthe cavity 204 above the rack arrangement 206. The transverse plate 291is provided with a large central irregularly-shaped aperture 292.

A grappler carrier 293 which includes an elongated horizontal carrierplate 294 is mounted for pivotal movement on the transverse plate 291.More particularly, a short vertical post or shaft 295 is secured at oneside of the plate 291 adjacent the central aperture 292. The post 295extends upwardly from the plate and pivotally supports one inner end ofthe elongated carrier plate 294, with the remainder of carrier plate 294extending across to' the other side of the aperture 292. The carrierplate 294 is supported in spaced relation above the transverse plate291. An elongated horizontally extending shaft structure 296 isrotatably supported below the carrier plate 294, extending generallylongitudinally and centrally of the elongated carrier plate. The shaftstructure 296 is supported for rotation by three vertical support plates297, 298, 299 which are secured to, and extend downwardly from, theunderside of the carrier plate 294. The support plates each extendtransversely of the elongated carrier plate 294 and are positioned atspaced-apart intervals along the carrier plate. One of the supportplates 297 is secured at the outer end of the carrier plate with anintermediate plate 298 and an inner plate 299 being progressively spacedinwardly from the outer support plate 297. The intermediate supportplate 298 has a greater height than the other two support plates and isprovided with roller means along its lower edge. The roller means restupon an upper surface of the transverse plate 291 to thereby support theouter end of the elongated carrier plate 294 while permitting itsrotation.

A gear 300 is secured on the shaft structure 296 between the outersupport plate 297 and the intermediate support plate 298 and is therebypositioned to engage a segment of a circular ring gear 302 which issecured to the upper surface of the transverse plate 291.

A large intermediate bevel gear 304 is rotatably disposed on the pivotpost 295. A two-part connector mechanism 306 provides a drivingrotational connection between the intermediate gear 304 and the innerend of the shaft structure 296. One part 306a of the connector mechanism306 is secured to the underside of the carrier plate 294. The other part306b of the connector mechanism 306, which includes a small bevel gear306a that engages the intermediate gear 304, is fixed to the uppersurface of the transverse plate 291. The two parts 306a and 30612 aremovable relative to one another about a vertical joining axis so thatthe driving connection between the gear 304 and the shaft structure 296will be maintained regardless of the rotational position of the carrierplate 294 about the pivot post 295. The large intermediate gear 304 isalso engaged by a bevel gear 308 which is fixedly secured on the innerend of a horizontal shaft structure 310 rotatably supported in theadjacent wall of the casing. The shaft structure 310 is drivinglyengaged to a suitable driving means 312 which is mounted on the outsideof the casing and which is selectively operable to rotate the gear 300and thereby cause the carrier plate 294 and the grappler 214 which itsupports, as will be described below, to assume any desired azimuthposition.

16 The illustrated fuel transfer cask 50 is also provided with means forpositioning the grappler 214 radially with respect to the pivot post295. A generally rectangular, horizontal, movable platform 320 issupported on the elongated carrier plate 294 for movement longitudinallyof that plate. The platform 320 is supported between a spaced-apartparallel pair of track members 322 which are supported on and extendlongitudinally of the plate 294. Each of the track members 322 isprovided with an elongated horizontal groove 323 in its opposed orinwardly directed vertical surface. Guide rollers (not shown) mounted onthe opposite longitudinal edges of the platform 320 are received in therespective grooves 323 to support the platform for movement.

The elongated carrier plate 294 is provided with an elongated, central,longitudinally extending aperture 325, and a generally cylindrical,hollow, vertical, grappler guide cylinder 326, which extends through andis supported intermediate its height by the movable platform 320,extends downwardly through the carrier plate aperture 325. Thedownwardly extending portion of the guide cylinder 326 also passesdownwardly through the aperture 292 of the transverse plate 291. Thelower end of the guide cylinder 326 is disposed a short distance abovethe actuating plate 280 of the retaining mechanism. The upwardlyextending portion of the guide cylinder 326 has mounted on its upper enda pulley support block 328. The block 328 is a generally fiat structuredisposed in a vertical plane that extends in general alignment with theelongated carrier plate 296. As will be described more fully, pulleyssupported by the block 328 maintain and guide cables, and the cablessupport and operate the grappler 214 for vertical movement through andbelow the guide cylinder 326.

The means for moving the platform 320 and the supported grappler 214radially toward and away from the pivot post 295 includes an elongated,horizontal, threaded shaft 334 which is rotatably supported above thecarrier plate 294 between a vertical post structure 335 extendingupwardly from the outer end of that plate and a vertical support plate336 extending upwardly from the inner portion of that plate. Aninternally threaded follower member 337 is disposed on the threadedshaft 334 for movement longitudinally of the shaft as the shaft isrotated. The follower member 337 is secured to the movable platform 320so that the movement of the follower produces like movement of theplatform. The inner end of the shaft 334 is connected by a two-partpivotal connector mechanism 338 to a horizontal shaft structure 340extending through and rotatably supported in the casing wall. The shaftstructure 340 is in driving engagement with radial positioning drivemeans 342 mounted on the outside of the casing. The connector mechanism338 is generally similar in construction to the two-part connectormechanism 306, having one part 338a supported by the vertical plate 336and operatively connected to the shaft 334. The second part 338b, Whichis pivotally connected to the first part 338a about a vertical axis, ismounted by a bracket 344 to the wall of the casing and operativelyconnected to the shaft structure 340. Selective operation of the drivemeans 342 serves to move the follower 337 longitudinally of the carrierplate 294 to thereby move the platform 320 and the grappler 214 towardor away from the pivot post 295. This radial movement, coupled with theazimuth movement afforded by the rotation of the carrier plate about thepivot post 295, permits selective positioning of the grappler 214 overan infinite number of positions relative to the underlying rackarrangement, and in particular permits the grappler 214 to be verticallyaligned above any selected reaction element.

In general, the grappler 214 is supported, vertically moved, andactuated by the selective operation of a pair of flexible cables: alower lift or hoist cable 348 and an upper actuator cable 350.

The lower lift cable 348 is secured at one end to a block 352 supportedat the upper end of the vertical post 335. The cable 348 then passesover a vertically extending lower outer pulley 354 supported for freerotation about a horizontal axis in the pulley block 328. The lift cable348 then extends vertically downwardly into the guide cylinder 326,passes through the grappler itself 214, and returns vertically upwardlywhere it passes over and around a vertically extending lower innerpulley 356, also supported for free rotation in the pulley block 328.The lift cable 348 then extends generally horizontally to a pulley 357mounted for free rotation about a vertical axis in a pulley block 358secured to the easing wall by a bracket 359. The blocks 352, 328 and 358generally lie in a common vertical plane and consequently the cable 348to this point has been confined to that common vertical plane. However,from the horizontal pulley 357 the lift cable 348 extends generallyhorizontally out of the plane, passing under and around a verticallyextending lower oifset pulley 360 mounted for free rotation by suitablemeans on the casing. The cable 348 extends vertically upwardly from thepulley 360, passing through a narrow aperture through the upper end wallof the casing. Finally, the cable 348 is wound about a suitable liftingdrum or reel 362 rotatably supported in a housing 364 mounted atop thecasing. The drum 362 is in driving engagement through a clutch-brakeconnector with and selectively rotatably by suitable motor means 366also mounted atop the casing.

The upper or actuator cable 350 i similarly supported and guided. Oneend of the actuator cable 350 is fixed to the block 352, from whence thecable extends around a vertical upper outer pulley 370 supported in theblock 328 into the guide cylinder 326, where it passes through thegrappler 214, and upwardly to an upper inner pulley 372, also mounted onthe block 328. The actuator cable 350 then extends horizontally to apulley 374 mounted in the block 358,,around an offset vertical pulley375, and upwardly through a suitable aperture or passageway in the upperend wall of the casing into the housing 364. Finally, the actuator cable350 is secured to and wound around a suitable actuator drum or reel 376rotatably supported in the housing 364. The actuator reel 376 is indirect driving engagement with the motor means 368.

To raise or lower the grappler 214, the cables 350 and 348 are bothmoved at the same rate by the motor means 368, which is operated torotate both reels 362 and 376. To actuate or operate the grappler 214,the connector 366 is operated to release the clutch and to apply thebrake to the lift cable drum or reel 362 while the actuator cable reel376 continues to rotate. The actuator cable 350 is thereby moved tocause relative movement of the parts of the grappler to cause engagementor disengagement by the fingers of the grappler with the element beinghandled.

It may be noted that the cables 348 and 350 in essence pivot around thevertical axis of the pulleys 357 and 374, which is in general alignmentwith the vertical pivot post 295. The portions of the cables between thepulleys 357 and 374 at one end and the block 352 at the other aredisposed in a common vertical plane and these portions of the cableremain generally in this plane incident to the pivoting movement of thecarrier plate 294 about the pivot post 295. In this connection, theblock 352 is fixedly secured to the carrier plate 294 through thevertical post 335 and the block 328 is also mounted on the carrierplate294 through the movable platform 320 and the guiding cylinder 326.While the platform 320 is movable toward and away from the axis of thepivot post 295 (which generally coincides with the axis of thehorizontal pulleys 357 and 374), the platform 320 is not capable ofrotationalor azimuth movement around that axis other than as a unit withthe carrier plate 294 and associated parts. Thus,-the platform 320 andthe guide cylinder 326 and the block 328, define a common vertical planewith the vertical post 335 and the block 352. The platform 320 and theparts it supports are movable only in that plane. The noted portions ofthe cables 348 and 350 are likewise maintained in this pivoting commonvertical plane, with the flexible cable arrangement also affording readymovement of the platform 320 and the grappler 214 toward and away fromthe axis of pivot. Movement of the platform, guide cylinder, and block328 toward the pivot merely causes rotation of the various pulleys and arepositioning of these parts, including the grappler 214, at moreinwardly located portions of the respective cables. It may particularlybe noted that the height of the grappler 214 remains unaffected by itsradial movement.

The illustrated grappler 214, shown generally in FIG- URE 8, is shown infurther detail in FIGURES 15 through 18.]As seen in FIGURE 15, thegrappler includes a generally cylindrical vertically extending hollowgrappler housing 378 which is open at its lower end and has a transversewall at its upper end. The housing 378 forms a generally cylindricalvertical central cavity 379. A pulley 380 for the lift cable 348 of thegrappler mechanism is mounted at an intermediate point within the cavity379 in such a manner that an open actuator assembly 381 is disposed inthe cavity around the pulley and vertically movable relative to thepulley.

The lift cable pulley 380 is positioned in the cavity 379 centeredbetween opposite sides of the cavity, and is supported on a short shaft382 for free rotation about a horizontal axis. The shaft 382 issupported by a hoist or lift pulley support block 383 which is fixedlymounted by means of a transverse support member 384 within the cavity.The lift pulley 380 and the associated supporting parts thus extendtransversely of the cavity 379 in general alignment with the plane ofthat pulley, being secured in position at opposed sides of the housing,with a space being left at either face side of the pulley 380. The lowerlift cable 348 extends down into the grappler, is looped under thepulley 380, and passes back upwardly. The cable passes throughappropriate openings or apertures in the upper end wall of the grapplerhousing. The lift cable 348 is wound on to or unwound. from its reel 362by the drive means 368 to selectively raise or lower the grapplerhousing which carries with it the other parts of the grappler.

As noted above, the actuator assembly 381 is vertically movable withinthe cavity 379. The illustrated actuator assembly 381 includes a pair ofelongated vertically disposed, opposed bands or strips 386 which extenddown the sides of the generally cylindrical cavity 379 at opposite facesides of the lift cable pulley 380 and associated mounting parts. Eachof the band 386 is curved or formed about a longitudinal vertical axisto generally conform to the contour of the housing cavity. The bands 386are secured at their upper ends to a transversely extending supportmember 387 on which a pulley block 388 is mounted. An actuator cablepulley 389, which is smaller than the pulley 380, is mounted in theblock 388 on a short shaft 390 for free rotation about a horizontalaxis. As shown in FIGURE 15, the pulleys 380 and 389 are disposed in agenerally common vertically extending plane which generally bisects thegrappler. The upper actuator cable 350 extends down into the grappler,is looped under the actuator cable pulley 389, and passes back upwardly.The cable 350 passes through a pair of suitable apertures or openings inthe upper end wall of the grappler housing.

The lower ends of the vertical bands 386 are secured to the upper end ofa generally cylindrically vertically extending weighted actuator element392 which is disposed below the lift cable pulley 380 and associatedsupport parts. An irregularly-shaped generally annular actuator block393 is secured around the lower end of the element 392. The illustratedactuator block 393 includes a set of three horizontally extending upperactuator pins 394 and a set of three horizontally extending loweractuator pins 395 (FIGURE 18).

The grappler 214 is provided with means to engage either a fuel rodelement 54 or a control rod guide tube element 53. More particularly,mounted in the lower end of the grappler housing 378 are two sets ofelongated vertically extending circumferentially-equallyspaced arms,hooks or members, one set of three, long, first,fuel-rd-element-engaging arms 396 and one set of three,alernately-spaced, shorter, second, guide-tube-element-engaging arms397. The arms 396 and 397 extend downwardly from the open lower end ofthe grappler housing 378, as shown generally in FIGURE 15. The arms 396and 397 are pivotally supported at their upper ends on pins 398 and 399,respectively, in a manner permitting the lower ends of the arms to pivotradially toward and away from the vertical center line of the grappler.Each of the'three arms 396 is provided'with a formed elongated verticalslot 400 in which one of the actuator pins 395 of the actuator assemblyis received. Similarly, each of the arms 399 is provided with anelongated formed vertical slot 401 in which one of the actuator pins 394is received. In general, the vertical movement of the actuator assembly381 relative to the grappler housing 379 causes the arms 396 and 397 toopen and close.

More particularly, each of the three fuel-rod-elementengaging arms 396is provided with a radially-inwardlydirected circumferentially-enlargedprojection or finger 402 (FIGURE 16) and the vertical slot 400 of eachof these arms 396 is provided with a radially inwardly offset portion403 at the lower end of the slot. Thus, when the actuator assembly 381is lowered relative to the grappler housing 378, thefuel-r0d-element-engaging arms 396 are spread open or outwardly by theaction of the actuator pins 395 moving into the offset lower end portion403 of their respective slots. When the actuator assembly 381 is raisedrelative to the grappler housing, the arms 396 are pivoted or drawnradially inwardly. This causes the enlarged fingers 402 to set under anannular lip or ledge 54a provided by the head at the upper end of a fuelrod element 54. As shown best in FIGURE 16, the fingers 402 arecircumferentially equally spaced and provide firm three-point engagementof the fuel rod element to prevent its slippage or misalignment. Whilethe weight of the fuel rod element 54 would tend to maintain theaforesaid connection, positive vertical location of the grapplerrelative to the fuel rod element is provided by an engaging andpositioning plug 404 secured to the grappler and extending downwardlyfrom the center thereof through the open lower end of the housing. Theplug 404 is provided with a flared central recess 405 which engages thegenerally conical upper end of the fuel rod element 54 and ensuresmaintenance of the positive connection between the grappler and the fuelrod element.

Each of the control-rod-guide-tube-element-engaging arms 397 is providedwith an outwardly extending circumferentially enlarged finger orprojection 406 (FIG URE 16 at its lower end and the vertical slot 401 ofeach arm is provided with a radially outwardly offset portion 407 at thelower end of the slot. When the actuator assembly 381 is loweredrelative to the grappler housing, the arms 397 are pivoted or drawninwardly by the action of the actuator pins 394 entering the lowerportions 407 of their respective slots. When the actuator assembly israised relative to the grappler housing, the arms 397 are pivotedradially outwardly, causing the en larged fingers 406 to seat in anannular groove or recess 53a that extends around the inside of thecontrol rod guide tube element adjacent its upper end. The proper heightof the grappler relative to the control rod guide tube element 53 isdefined by the engagement of the lower end of the grappler housing 378with the upper end of the guide tube element. This also ensures that thepositive connection between the grappler and the guide tube element ismaintained.

It will of course be understood that while the movement of the actuatorassembly 381 operates all of the arms 396 and 397, at any given time thegrappler 214 will only be operated with respect to one of the elements,i.e., either a fuel rod element 54 or a control rod guide tube element53. Both of the types of elements 54 and 53 are illustrated in FIGURE 15in broken line merely to illustrate the alternate functions or uses ofthe grappler.

Thus, with the grappler actuator assembly 381 lowered, the entiregrappler 214 is lowered to position the appropriate arms in properposition relative to the element to be handled. The grappler is loweredby the drive means 368 operating both reels 376 and 362 at the same rateto unwind both cables 350 and 348 at the same rate. Then the grappleractuator assembly 381 is raised relative to the grappler housing andother grappler parts to a position such as shown in FIGURE 15 to causethe grappler fingers to engage the element being handled. This relativemovement of the actuator assembly 381 is achieved by releasing theclutch and engaging the brake between the lift cable reel 348 and thedrive means 368. Then the drive means 368 will only function to rotatethe actuator cable reel 376 and not the lift cable reel 362. When it isdesired to raise or lower the element being held, both of the cables 350and 348 are again operated at the same rate so that the actuatorassembly 381 is maintained in raised, locking position relative to thegrappler housing 378.

To release the element, the aforesaid action is reversed, i.e., theactuator assembly 381 is lowered relative tothe grappler housing to movethe fingers 402 and 406 out of engagement with the element beinghandled.

Suitable locks and safety features may be incorporated to preventimproper, dangerous or hazardous operation of the grappler mechanism.

Thus, the same compact, relatively simple, yet sure and efiectivemechanism or arrangement which serves to raise and lower the grappleralso serves to operate the grasping or connecting fingers.

The operation of the fuel transfer cask 50 may now be more readilyunderstood.

To remove elements from the reactor 30, the empty cask 50 is positionedover a selected empty nozzle 51, fixedly connected to that nozzle by anisolation valve, and is operated to remove the seven center elementsfrom directly below the nozzle. In this connection, the rack arrangement206 is rotated to vertically align 208 with a selected one of the centerelements. The grappler mechanism 290 is operated to position thegrappler 214 directly above the selected center element. The inner doorsection 216a is rotated to align at least partially its aperture 210awith the aperture 21% of outer door section 216b and the door sectionsare rotated as a unit to vertically align the small access pasageway 210with the selected center element. The isolation valve is also opened.The retaining mechanism 260 is operated to open or raise the platformsor bars 262 of the empty compartments and the grappler 214 is loweredthrough the selected compartments with which the grappler is aligned,through the underlying access passageway 210, through the isolationvalve and nozzle 51, into the primary reactor vessel 32 (FIGURE 1). Thegrappler engages the selected center element, is actuated by the cablesto connect to that element, and lifts the element essentially straightupwardly through the nozzle and the isolation valve into the alignedcompartment. The element is raised sufficiently in the compartment toclear the platform 262 and the platforms are then caused to pivot orswing down to their closed or horizontally extending position across thebottom of the compartment. The element is lowered to its platform, thegrappler is actuated to disconnect from the element, and the grappler israised clear of the rack arrangement.

Then the procedure is repeated for another center element. The grapplerand the access passageway 210 are repositioned laterally to verticallyalign with another of the center elements. The latch mechanism isoperated

